Air data sensors are typically mounted to an aircraft and are capable of measuring the movement of fluids relative to the same. Depending upon the application, various air data sensors may take several measurements, including total air pressure (also called Pitot pressure), static air pressure, total air temperature, static air temperature, angle of attack, and angle of slip. In general, smaller manually flown aircraft require fewer of these measurements e.g., only static air pressure and total air pressure, while larger aircraft, that operate under more regulation and have more automation, may require the complete set of measurements.
Air data sensors may comprise various probes and transducers that supply signals to a computer box or integrated computer box/display device to calculate the speed, direction, altitude and other aerodynamic information required to pilot an aircraft. A Pitot-static probe, shown in FIG. 1, is typically used to measure the total and static pressure. This probe has ports connected to pressure transducers to effectuate these measurements. The total air temperature is usually measured with a ported probe, shown in FIG. 2. A ported probe is similar in concept to a Pitot tube, but the port leads to a temperature transducer instead of a pressure transducer and ported probes normally employ exit ports to reduce the response time of the instrument. Static air temperature is normally measured using an opening leading to a transducer instead of an external probe since this measurement is largely uninfluenced by air velocity. An angle of attack (AOA) probe measures the angle the aircraft is moving relative to the air stream. One style of angle of attack probe, shown in FIG. 3, employs a rotating fin or blade that aligns itself with the air stream and outputs a signal proportional to the angle of rotation. An angle of slip probe is similar to the angle of attack probe, but the fin or blade is mounted pointing up or down instead of right or left.
Dual function probes such as the Pitot probe, which measures both static and total pressure, are known in the art. See, for example, U.S. Pat. No. 6,002,972 which discloses an airplane wing fitted with orifices in order to take pressure measurements at two locations along the surface of the wing. See also, U.S. Pat. Nos. 5,731,507 and 5,628,565 that disclose dual function sensors that take both pressure and temperature measurements.
However, prior to the present invention, no one was able to integrate pressure, temperature, and angle of attack probes and transducers in a single, compact and robust assembly. Accordingly most prior art applications required the use of multiple analog sensors. Not only must all of these sensors be integrated into the aircraft instrumentation, thereby increasing production costs, employing multiple sensors also place additional protrusions on the aircraft's fuselage, increasing the total drag force on the aircraft and reducing its effective flying range.
Thus, there is a need for an improved multifunction air data sensor in which all probes and transducers are integrated in a single compact, robust assembly that either communicates with the air data system computer digitally or replaces the air data system computer entirely, thereby reducing the weight and the cost of an airplane's instrumentation.